* Galileo was forced to publicly recant his theories (1633). (Click on button at lower right of the gallery for a biography of Galileo's life, findings, and contributions to science.)

* Greenwich Observatory founded (1675).

k * Charon, Pluto's moon, discovered (1978).

* NASA Aircraft Automated Advisory System demonstrated at Manassas Municipal Airport, VA, (1980).

* Comet Graet put on a bright night show in the heavens (1881).

* Second attempt at launching the super Soviet rocket type G-1 failed when booster exploded at altitude of 12 km (1971).

* First use of radar to detect an aircraft (1930).

* First use of the term "flying saucer" appeared in a report (1947).

* Hale detected magnetic fields on the Sun (1908).

This is a sketch of a photo of lenticular cloud formations. Clouds and meteoro-logical balloons are sometimes mistaken for flyging saucers. However, many sightings have not been explained by science. They are identified as Unidentified Flying Objects or "UFOs" for short.

* Astronaut Bernard A. Harris born in Temple, Texas (1956).

* First newspaper ads for airplanes (1909).

* Launch of STS-4 (1982).

* One of the largest solar flares in recorded history (1984).

* Dog killed by 18-lb meteorite. (Nakhla, Egypt, 1911).

* Cosmonaut Lt. Col. Georgi Dobrovolsky killed in reentry of his Soyuz 11 spacecraft (1971).

* First flight of Lockheed transport aircraft C-5A (1968).

* Great comet of 1861 seen; it was the apparent source of the Perseid meteors.

* Tunguska fireball (1908).